CN108469803A - It safeguards judge index apparatus for predicting, volume control device and safeguards judge index estimating method - Google Patents

Abstract

Present invention offer safeguards judge index apparatus for predicting, volume control device and safeguards judge index estimating method.To judging whether volume control device and its relevant device need the judge index safeguarded to infer in the operation of device.The present invention maintenance judge index apparatus for predicting include：Valve opening acquisition unit (3) consists of the aperture for obtaining the valve when the flow of fluid in controlling the flow control of the flow of fluid using valve is maintained at prespecified target flow；And flow rate upper limit inferring portion (4), consist of based on aperture and the relationship of the flow of fluid to valve be subject to it is approximate obtained by function and the valve got by valve opening acquisition unit (3) aperture, it will be assumed that reach the maintenance judge index that the flow rate upper limit value under upper limit case is inferred as volume control device in the aperture of the time point valve of the acquisition.

Description

Maintenance judgment index inference device, flow control device and maintenance judgment index deduction device method

technical field

The invention relates to a technology for inferring the judgment index of whether flow control devices such as mass flow controllers and related equipment such as filters need to be maintained.

Background technique

In semiconductor manufacturing equipment and the like, a flow control device such as a mass flow controller as shown in FIG. 6 is used to introduce a material gas or the like into a vacuum chamber at a constant flow rate (refer to Patent Document 1). In FIG. 6 , 100 is a main body block, 101 is a sensor unit, 102 is a head of the sensor unit 101, 103 is a fluid sensor mounted on the head 102, 104 is a valve, and 105 is a fluid flow sensor formed inside the main body block 100. 106 is an opening on the inlet side of the flow path 105 , and 107 is an opening on the outlet side of the flow path 105 .

The fluid flows into the flow path 105 from the opening 106 and is discharged from the opening 107 through the valve 104 . The fluid sensor 103 measures the flow rate of fluid flowing in the flow path 105 . A not-shown control circuit of the mass flow controller drives the valve 104 so that the flow rate of the fluid measured by the fluid sensor 103 coincides with a set value.

When the flow rate of the material gas is continuously controlled by such a mass flow controller, the influence of the components contained in the material gas may cause contamination to adhere to the mass flow controller itself or to the filter provided on the flow path of the material gas. and other related equipment and so on.

Therefore, a device for correcting the valve opening by operating and correcting the valve opening has been proposed so that flow rate errors and pressure errors occur only within the allowable accuracy range over the entire measurement range of the fluid sensor built in the mass flow controller. . However, in the diagnostic mechanism disclosed in Patent Document 2, there is a problem that although it is possible to diagnose whether the error between the measured value of the fluid sensor and the actual flow rate is tolerable in accuracy, it is necessary to install The valve on the road is kept in a fully closed state, or the valve is changed from a fully closed state to a developed state, making it difficult to diagnose during the operation of the device. When the mass flow controller is installed in, for example, a semiconductor manufacturing apparatus, it is difficult to stop the entire semiconductor manufacturing apparatus for diagnosis of the mass flow controller.

In addition, in the diagnosis mechanism disclosed in Patent Document 2, when the diagnosis of the mass flow controller is performed at the time when the operation of the semiconductor manufacturing apparatus is stopped, there is a problem in that the flow of the fluid into the mass flow controller occurs during the stop of the operation. Afterwards, the flow path of the flow controller needs to change the valve to the fully closed state, and the diagnostic work takes time and effort. In semiconductor manufacturing equipment and the like, if the necessity of maintenance can be judged during the operation of the equipment, it will be easier to perform operation management, so improvement is sought.

prior art literature

patent documents

Patent Document 1: Japanese Patent Laid-Open No. 2008-039588

Patent Document 2: Japanese Patent No. 5931668

Contents of the invention

The problem to be solved by the invention

The present invention is made to solve the above problems, and its purpose is to provide a maintenance index estimation device, a flow control device and a maintenance index that can infer whether the flow control device and its related equipment need to be maintained during the operation of the device. Inference method.

technical means to solve problems

The maintenance judgment index estimating device of the present invention is characterized by comprising: a valve opening acquisition unit configured to acquire when the flow rate of the fluid is maintained at a predetermined target flow rate in the flow rate control using a valve to control the flow rate of the fluid; the opening degree of the valve; and a flow upper limit estimation unit configured based on a function obtained by approximating the relationship between the opening degree of the valve and the flow rate of the fluid and obtained by the valve opening degree acquisition unit The opening degree of the valve is estimated as the maintenance judgment index of the flow control device by assuming that the opening degree of the valve reaches the upper limit at the acquired time point.

In addition, a configuration example of the maintenance judgment index estimation device of the present invention is characterized in that the flow rate upper limit estimation unit sets the upper limit of the opening degree of the valve corresponding to the flow rate upper limit value to 100%.

In addition, a configuration example of the maintenance judgment index estimating device of the present invention is characterized in that the function is defined by at least a term related to the opening degree of the valve and a gain which is a numerical value multiplied by the term, and the The flow rate upper limit estimation unit estimates the flow rate upper limit based on an expression obtained from the function assuming that the gain decreases with time and the opening degree of the valve acquired by the valve opening degree acquisition unit. value.

In addition, a configuration example of the maintenance judgment index estimation device of the present invention is characterized in that the function is a function obtained by approximating a nonlinear relationship between the opening degree of the valve and the flow rate of the fluid, and is similar to that of the valve. The opening-related terms are expressed using exponential functions.

In addition, a configuration example of the maintenance judgment index estimation device of the present invention is characterized in that the function is a function obtained by approximating a nonlinear relationship between the opening degree of the valve and the flow rate of the fluid, and is similar to that of the valve. The opening-related terms are expressed using fractional functions.

In addition, one configuration example of the maintenance judgment index estimation device of the present invention is characterized in that the flow rate upper limit estimation unit is composed of a gain calculation unit and a flow rate upper limit calculation unit, and the gain calculation unit estimates the flow rate upper limit value based on At the current time point, the valve opening obtained by the valve opening acquisition unit and the target flow rate are used to calculate the gain at the current time point, and the flow rate upper limit calculation unit is based on the gain calculated by the gain calculation unit To calculate the flow upper limit.

In addition, one configuration example of the maintenance judgment index estimating device according to the present invention further includes an estimation result output unit for numerically displaying the upper limit value of the flow rate estimated by the upper limit estimating unit.

In addition, one configuration example of the maintenance judgment index estimating device of the present invention further includes an estimation result output unit that issues an alarm when the flow rate upper limit value estimated by the flow rate limit estimating unit is less than a predetermined threshold value.

In addition, the flow control device of the present invention is characterized in that it includes: a flow measurement unit that measures the flow rate of fluid flowing in the flow path; a valve that is provided on the flow path; and a flow control unit that operates the valve. so that the flow rate measured by the flow rate measurement unit coincides with a predetermined target flow rate; and maintenance judgment index estimation means, and the valve opening degree acquisition unit of the maintenance judgment index estimation means acquires the The opening degree of the valve provided on the flow path.

In addition, the maintenance judgment index estimation method of the present invention is characterized by including: a first step of acquiring the flow rate of the fluid when the flow rate of the fluid is maintained at a predetermined target flow rate in the flow control using a valve to control the flow rate of the fluid; the opening degree of the valve; and the second step, based on the function obtained by approximating the relationship between the opening degree of the valve and the flow rate of the fluid and the opening degree of the valve obtained by the first step, The upper limit value of the flow rate when the opening degree of the valve reaches the upper limit at the acquired time point is estimated as a maintenance judgment index of the flow rate control device.

The effect of the invention

According to the present invention, it is possible to infer the judgment index (flow upper limit value) of whether the flow control and its related equipment need to be maintained during the operation of the device. As a result, it is easy for the operator to perform operation management of the semiconductor manufacturing equipment and the like provided with the flow rate control device. In addition, in the present invention, it is possible to significantly reduce the time and effort required to determine whether or not maintenance is necessary.

Description of drawings

FIG. 1 is a diagram showing an example of the relationship between the opening degree of a valve provided in a mass flow controller and the flow rate of a fluid.

2 is a diagram showing another example of the relationship between the opening degree of a valve provided in the mass flow controller and the flow rate of a fluid.

FIG. 3 is a block diagram showing the configuration of a flow control device according to an embodiment of the present invention.

FIG. 4 is a flowchart illustrating the flow control operation of the flow control device according to the embodiment of the present invention.

FIG. 5 is a flowchart illustrating the maintenance judgment index estimation operation of the flow rate control device according to the embodiment of the present invention.

Fig. 6 is a cross-sectional view of a mass flow controller.

Detailed ways

In most cases, the purpose of a mass flow controller is to maintain a steady flow of fluid at a target flow rate determined in a predetermined manner. Therefore, on the premise of such a use, it is possible to estimate the influence of clogging of the filter, etc. under a highly reliable detection condition. Specifically, a state in which an arbitrary target flow rate is stably maintained is detected, and a valve opening indication signal under this condition is acquired.

Considering the clogging of the filter installed upstream of the mass flow controller, the flow rate that can be achieved in the state where the valve opening is saturated to 100% at this point in time is the controllable flow rate at that point in time. The upper limit value, in other words, it is effective to infer the upper limit value and judge whether to perform maintenance. Therefore, the inventor conceived the idea of acquiring highly reliable valve opening information based on the unique operating conditions of the mass flow controller, and using the flow rate upper limit value estimated therefrom (for example, the estimated flow rate when the valve opening is 100%) as The judgment indicator of whether maintenance is required is appropriate.

[Example]

Embodiments of the present invention will be described below with reference to the drawings. Patent Document 2 shows that when the opening degree of a valve provided in a mass flow controller is changed linearly with time, the higher the opening degree side, the lower the flow rate of the fluid flowing in the flow path. The less the flow volume changes. It can be seen from this that the valve opening degree MV and the flow rate PV have a nonlinear relationship, and the higher the opening degree side, the smaller the change amount of the flow rate PV relative to the change amount of the opening degree MV. The outline of the characteristics of this mass flow controller is shown in FIG. 1 . In addition, in the example of FIG. 1, the flow rate PV is normalized to the value of 0-100%. The characteristic shown in FIG. 1 is a nonlinear convergence phenomenon, so it can be expressed by the exponential function of the following formula.

PV=K{1.0-exp(-MV/A)}···(1)

Thus, a function approximating the relationship between the valve opening MV and the flow rate PV is defined by a constant term (1.0), a term related to the valve opening MV, and a gain K that is a numerical value multiplied by these terms. A in Equation (1) is a coefficient that gives a nonlinear convergence state. The curve cur1 of Fig. 1 represents the initial characteristic of the mass flow controller. Based on the supply pressure that can be grasped in advance, set the flow rate PV to reach the maximum value of 100% when the valve opening MV = 100%. In addition, combined with ordinary nonlinear images, the curve cur1 can be an index of the coefficient value like the following formula function to perform.

PV＝104.0{1.0-exp(-MV/30.0)}···(2)

K=104.0 and A=30.0 in the formula (2) are one example of these numerical values. In the case of clogging of a filter or the like installed on the flow path, it can be inferred that the characteristic of the mass flow controller downstream of the filter, that is, the nonlinearity of the valve itself does not change, so the coefficient A can be regarded as fixed. Therefore, it is assumed that only the gain K decreases due to clogging of the filter or the like.

After judging whether the mass flow controller and related equipment of the mass flow controller need to be maintained, although it is speculated that several factors will affect the running time of the mass flow controller, it is assumed that the gain K is roughly proportional to the running time, that is, It is more appropriate to reduce at a certain moderate rate without a sharp deterioration.

Here, the predetermined target flow rate PVx is assumed to be PVx=60.0%. That is, the most standard numerical value given as the flow rate setting value SP of the mass flow controller is SPx=60.0%. Assuming that the initial state valve opening of the mass flow controller for setting the flow rate of the fluid to PVx=60.0% is MV1, MV1=25.8% from the curve cur1. Since the coefficient A=30.0 of the nonlinear characteristic can be known in advance, the gain K1 in the initial state can be calculated inversely as the following formula from PVx=60.0% and MV1=25.8%. In addition, in this initial state, the flow rate (flow rate upper limit value PVh) when the valve opening is 100% is PVh=100% as described above.

K1=PVx/{1.0-exp(-MV1/A)}

=60.0/{1.0-exp(-25.8/30.0)}=104.0···(3)

Next, the valve opening MV for maintaining the target flow rate PVx is acquired at the point in time when the operating time of the mass flow controller at which the clogging degree of the filter has occurred has elapsed. In this case, the target flow rate PVx may be a value different from the target flow rate PVx in the initial state. Here, the target flow rate PVx is set to 40.0%. For example, when 72 hours have elapsed from the start of the operation, MV2 = 16.2% is detected as the valve opening MV for maintaining the target flow rate PVx = 40.0%. This value means that the pressure at the point of flow into the mass flow controller decreases due to clogging of the filter, and the valve opening MV for maintaining the target flow rate PVx=40.0% must be changed to MV2=16.2%.

The gain K2 at the point in time when 72 hours have passed after the start of the operation can be reversely calculated as in the following formula based on PVx=40.0% and MV2=16.2%.

K2=PVx/{1.0-exp(-MV2/A)}

=40.0/{1.0-exp(-16.2/30.0)}=96.0···(4)

Therefore, the inferred gain K decreased from K1 = 104.0 in the initial state to K2 = 96.0 within 72 hours, a numerical decrease of only 8.0. In this case, the characteristic of the mass flow controller becomes like the curve cur2 of FIG. 1 . And, in the state of this cur2, the flow rate (flow rate upper limit value PVh) when the valve opening degree is 100% can be calculated as the following equation.

PVh＝96.0{1.0-exp(-100.0/30.0)}＝96.6···(5)

In this way, PVh=96.6% is the upper limit value of the controllable flow rate in the state of cur2, and it can be judged that the state is not serious. That is, it becomes a judgment index that the maintenance of the mass flow controller is not required yet.

Since it is assumed that the gain K decreases at a constant rate approximately in proportion to the operating time of the mass flow controller, it can be deduced that when about 72 hours have elapsed from the state of cur2, the gain K may decrease by about 8.0, and the mass The characteristic of the flow controller becomes like the curve cur3 (K3=88.0) in FIG. 1 . In this state of cur3, the flow rate (flow rate upper limit value PVh) when the valve opening is 100% can be calculated as follows. However, it is limited to the case where the gain K decreases at a constant speed.

PVh＝88.0{1.0-exp(-100.0/30.0)}＝84.9···(6)

When organizing the above, it is as follows. In the initial state (cur1), PVh=100% can be inferred from the actual performance of PVx=60.0% and MV1=25.8%. In the state (cur2) after 72 hours from the start of the operation, PVh=96.6% can be estimated from actual results of PVx=40.0% and MV2=16.2%. In the state (cur3) after another 72 hours, it can be estimated that PVh=84.9%.

Next, the valve opening degree MV for maintaining the target flow rate PVx is acquired at a point in time when time has elapsed. At this time, the target flow rate PVx=30.0% is set, and the detected MV4=19.8%. In this case, based on PVx=30.0% and MV4=19.8%, the gain K4 can be calculated inversely as in the following formula.

K4=PVx/{1.0-exp(-MV4/A)}

＝30.0/{1.0－exp(-19.8/30.0)}＝62.0···(7)

In this case, the characteristic of the mass flow controller is as shown in the curve cur4 of FIG. 1 . And, in the state of this cur4, the flow rate (flow rate upper limit value PVh) at a valve opening degree of 100% can be calculated as shown in the following equation.

PVh＝62.0{1.0-exp(100.0/30.0)}＝59.8···(8)

Thus, PVh=59.8% is the upper limit of the controllable flow rate in the cur4 state. As past actual results, there is an example in which the target flow rate PVx is set to PVx=60.0, and since PVh=59.8% is lower than the past target flow rate PVx, it is judged as a severe state. That is, it becomes a judgment index that maintenance of the mass flow controller is required.

Based on the above, the steps of obtaining the judgment index for the necessity of maintenance of the mass flow controller and its related equipment can be organized into the following (I) and (II). According to this embodiment, even when it seems that there is a margin in the valve opening due to the low flow rate and low opening degree (the valve opening degree is sufficiently far from the upper limit) for control, an appropriate judgment index can be obtained. .

(I) The valve opening MV for maintaining the flow rate of the fluid at an arbitrary target flow rate PVx can be obtained. The gain K is calculated based on the valve opening MV. However, the non-linear coefficient A is predetermined.

K=PVx/{1.0-exp(-MV/A)}···(9)

(II) Calculate the flow when the valve opening MV reaches 100% of the upper limit as the controllable flow upper limit PVh, and use the flow upper limit PVh as an index for judging whether the mass flow controller and its associated equipment need maintenance.

PVh＝K{1.0-exp(-100.0/A)}···(10)

In addition, the same method can be applied even if it is not an exponential function as long as it is a function that can approximate the nonlinearity shown in FIG. 1 . For example, if the following fractional function is used, the nonlinearity between valve opening and flow rate can be described only by four arithmetic operations.

PV＝K[{-A/(MV+B)}+C]

=1.0[{-3130.0/(MV+25.0)}+125.2]···(11)

K＝PVx/[{-A/(MV+B)}+C]···(12)

PVh＝K/[{-A/(100.0+B)}+C]···(13)

Like the expression (1), the function of the expression (11) is defined by a constant term (C=125.2), a term related to the valve opening MV, and a gain K multiplied by these terms. From the formulas (11) to (13), the characteristics of the mass flow controller can be shown in FIG. 2 similar to FIG. 1 . In FIG. 2 , the gain K1 in the state of the curve cur1 is 1.0, the gain K2 in the state of the curve cur2 is 0.923, the gain K3 in the state of the curve cur3 is 0.846, and the gain K4 in the state of the curve cur4 is 0.596. That is, similarly to the example in FIG. 1 , the gain K decreases at a constant rate in proportion to the operation time.

Next, the configuration of the flow control device (mass flow controller) of this embodiment will be described. As shown in FIG. 3 , the flow control device of this embodiment includes: a flow measurement unit 1 that measures the flow rate of the fluid flowing in the flow path; a flow control unit 2 that operates the valve so that the flow rate measured by the flow measurement unit 1 The flow rate coincides with the target flow rate PVx; the valve opening acquisition unit 3 acquires the valve opening MV when the flow rate of the fluid is maintained at the predetermined target flow rate PVx during the flow control; the flow rate upper limit estimation unit 4 assumes that the valve opening is The flow upper limit value PVh when the valve opening reaches the upper limit (for example, 100%) at the time point of acquisition of the opening MV is estimated as a maintenance judgment index; information about the results.

Next, the operation of the flow control device of this embodiment will be described with reference to FIGS. 4 and 5 . FIG. 4 is a flow chart illustrating the flow control operation, and FIG. 5 is a flow chart illustrating the maintenance judgment index estimation operation.

The flow rate measuring unit 1 continuously measures the flow rate of the fluid flowing in the channel (the channel 105 in FIG. 6 ) (step S100 in FIG. 4 ). This flow measurement unit 1 corresponds to the fluid sensor 103 shown in FIG. 6 and is a well-known structure provided in a mass flow controller.

The flow rate control unit 2 continuously operates the valve (valve 104 in FIG. 6 ) so that the flow rate of the fluid measured by the flow rate measurement unit 1 coincides with, for example, a target flow rate PVx set by an operator (step S101 in FIG. 4 ). This flow control unit 2 is also a known configuration provided in a mass flow controller.

In this way, the processes of steps S100 and S101 are repeatedly executed at predetermined intervals (for example, 50 msec.) until, for example, an operator instructs to end the operation of the device (Yes in step S102 in FIG. 4 ).

On the other hand, the valve opening acquisition unit 3 acquires the valve opening MV (target maintenance valve opening) when the flow rate of the fluid is maintained at the target flow rate PVx (step S200 in FIG. 5 ). Specifically, when the absolute value of the deviation between the flow rate measured by the flow rate measurement unit 1 and the target flow rate PVx has been continuously within a predetermined value during the period from a certain time ago to the current time point, the valve opening acquisition unit 3. Determine that the flow rate of the fluid is maintained at the target flow rate PVx, and acquire the valve opening MV at the current point in time. The value of the constant time t is set in the valve opening acquisition unit 3 as a predetermined value.

In addition, although it is also possible to detect the valve opening itself, it is not strictly necessary to detect the valve opening in terms of installation. The signal output from the flow control unit 2 to the valve (for example, the valve opening indication signal or the valve driving current) is acquired and based on this Signal to judge the valve opening.

Next, based on the valve opening degree MV (target maintenance valve opening degree) acquired by the valve opening degree acquisition unit 3, the flow rate upper limit estimation unit 4 assumes that the valve opening degree reaches the upper limit (for example, 100%) at the acquisition time point. The lower flow rate upper limit PVh is estimated as a judgment index of a controllable flow rate. As shown in FIG. 3 , the flow rate upper limit estimation unit 4 is composed of a gain calculation unit 40 which calculates a gain K and a flow rate limit calculation unit 41 which calculates a flow rate upper limit value PVh.

The gain calculation unit 40 of the flow rate upper limit estimation unit 4 calculates the gain K at the current point in time at which the flow rate upper limit value PVh is to be calculated by using Equation (9) (step S201 in FIG. 5 ). The coefficient A of the formula (9) is set in the flow rate upper limit estimation unit 4 as a predetermined value. In order to know the coefficient A, for example, a flow rate test of the flow control device may be performed in advance to investigate the value of the coefficient A.

Then, the flow upper limit calculating unit 41 of the flow upper limit estimating unit 4 calculates the flow upper limit value PVh by the expression (10) based on the gain K calculated by the gain calculating unit 40 (step S202 in FIG. 5 ). As above, the processing of the flow rate upper limit estimation unit 4 ends.

The estimation result output unit 5 outputs the estimation result of the flow rate upper limit estimation unit 4 (step S203 in FIG. 5 ). As an output method of the estimation result, there are, for example, numerical display of the flow rate upper limit PVh, alarm output based on the flow rate upper limit PVh, transmission of information of the estimation result to the outside, and the like. In the case of an alarm output, when the flow rate upper limit value PVh is less than a predetermined threshold value (for example, less than 60%), it is only necessary to turn on the LED for notifying the alarm.

The valve opening acquisition unit 3, the flow upper limit estimation unit 4, and the estimation result output unit 5 repeatedly perform the processing of steps S200 to S203 in accordance with each predetermined period ΔT (for example, 24 hours), until, for example, an operator instructs to end the operation of the device. So far (Yes in step S204 in FIG. 5).

Based on the above, in this embodiment, it is possible to infer the judgment indicator (flow upper limit value PVh) whether maintenance is required for the flow control device and its related equipment (filters installed on the flow path, etc.) during the operation of the device. An operator can judge whether or not a serious situation requiring maintenance has been reached based on the estimation result of the flow rate control device, so it is easy to perform operation management of a semiconductor manufacturing device or the like. In addition, in this embodiment, since the work of flowing fluid into the flow path of the mass flow controller is not required during the stoppage of the semiconductor manufacturing apparatus, it is possible to greatly reduce the labor required for determining whether maintenance is required.

In addition, when the valve opening acquiring unit 3 determines that the flow rate of the fluid is not maintained at the target flow rate PVx, the valve opening MV cannot be acquired, and thus the flow rate upper limit value PVh cannot be calculated in this case.

In addition, the present embodiment can be applied even when the target flow rate PVx changes halfway, but the valve opening acquisition unit 3 determines whether the flow rate of the fluid is maintained at the target flow rate PVx for a certain period of time t (t<ΔT) , the target flow PVx needs to be maintained at the same value. When the target flow rate PVx changes within a certain period of time t, acquisition of the valve opening degree MV cannot be performed.

Furthermore, the flow rate upper limit estimation unit 4 calculates the gain K and the flow rate upper limit PVh using Expressions (12) and (13) instead of Expressions (9) and (10). Coefficients A, B, and C of Expression (12) and Expression (13) are set in the flow rate upper limit estimation unit 4 as predetermined values. In order to grasp the coefficients A, B, and C, for example, a flow test of the flow control device may be performed in advance.

In addition, in this embodiment, all the configurations shown in FIG. 3 are provided in the flow control device (mass flow controller), but the present invention is not limited thereto. It is also possible to set the valve opening acquisition unit 3, the flow upper limit estimation unit 4, and the estimation result output unit 5 as a maintenance judgment index estimation device in a host device (such as a programmable logic controller PLC), and together with the flow measurement unit 1 It is used in conjunction with the ordinary micro-flow controller of the flow control unit 2.

The flow control device described in this embodiment can be realized by a computer including a CPU (Central Processing Unit), a storage device, and an interface, and a program for controlling these hardware resources. Likewise, the maintenance judgment index estimation device composed of the valve opening degree acquisition unit 3 , the flow rate upper limit estimation unit 4 , and the estimation result output unit 5 can be realized by a computer and a program. The CPU of each device executes the processing described in the present embodiment according to the programs stored in the respective storage devices. Thus, the maintenance judgment index estimation method of this embodiment can be realized.

Industrial availability

The present invention can be applied to the technology of managing the flow control device and its related equipment.

Symbol Description

1...Flow measurement unit, 2...Flow control unit, 3...Valve opening acquisition unit, 4...Flow limit estimation unit, 5...Estimation result output unit, 40...Gain calculation unit, 41...Flow limit calculation unit.

Claims (10)

1. A maintenance judgment index inference device, characterized in that, comprising: a valve opening acquisition unit configured to acquire the opening of the valve when the flow rate of the fluid is maintained at a predetermined target flow rate in the flow control of controlling the flow rate of the fluid using a valve; and The flow rate upper limit estimation unit is configured based on a function obtained by approximating the relationship between the opening degree of the valve and the flow rate of the fluid, and the opening degree of the valve acquired by the valve opening degree acquiring unit. , the upper limit value of the flow rate under the assumption that the opening of the valve reaches the upper limit at the acquired time point is estimated as the maintenance judgment index of the flow control device. 2. The maintenance judgment index derivation device according to claim 1, characterized in that: The flow rate upper limit estimation unit sets the upper limit of the opening degree of the valve corresponding to the flow rate limit value to 100%. 3. The maintenance judgment index derivation device according to claim 1 or 2, characterized in that, said function is defined by at least a term related to the opening of said valve and a gain being a value multiplied by this term, The flow rate upper limit estimating unit estimates the flow rate based on an expression obtained from the function assuming that the gain decreases with time, and the opening degree of the valve acquired by the valve opening degree acquiring unit. Upper limit. 4. The maintenance judgment index derivation device according to claim 3, characterized in that: The function is a function obtained by approximating the nonlinear relationship between the opening degree of the valve and the flow rate of the fluid, and items related to the opening degree of the valve are represented by exponential functions. 5. The maintenance judgment index derivation device according to claim 3, characterized in that: The function is a function obtained by approximating the nonlinear relationship between the opening degree of the valve and the flow rate of the fluid, and items related to the opening degree of the valve are represented by fractional functions. 6. The maintenance judgment index derivation device according to claim 3, characterized in that: The flow upper limit inference part includes: a gain calculation unit that calculates the current time point based on the valve opening acquired by the valve opening degree acquisition unit and the target flow rate at the current time point where the flow rate upper limit value is to be estimated. gain; and The flow rate upper limit calculation unit calculates the flow rate upper limit value based on the gain calculated by the gain calculation unit. 7. The maintenance judgment index estimation device according to claim 1 or 2, further comprising an estimation result output unit for numerically displaying the flow upper limit value estimated by the flow upper limit estimation unit. 8. The maintenance judgment index estimation device according to claim 1 or 2, further comprising an estimation result output unit that, when the upper limit value of the flow rate estimated by the upper limit estimation unit of the flow rate, is less than a predetermined threshold value, Send out a warning. 9. A flow control device, characterized in that it comprises: a flow measurement unit that measures the flow rate of fluid flowing in the flow path; a valve disposed on the flow path; a flow rate control unit that operates the valve so that the flow rate measured by the flow rate measurement unit coincides with a predetermined target flow rate; and According to the maintenance judgment index inference device according to any one of claims 1 to 8, The valve opening acquisition unit of the maintenance judgment index estimating device acquires an opening of the valve provided on the flow path. 10. A maintenance judgment index inference method, characterized in that it comprises: Step 1 of obtaining the opening degree of the valve when the flow rate of the fluid is maintained at a predetermined target flow rate in the flow control using the valve to control the flow rate of the fluid; and In the second step, based on the function obtained by approximating the relationship between the opening degree of the valve and the flow rate of the fluid and the opening degree of the valve obtained in the first step, it is assumed that at the time of the acquisition The flow upper limit when the opening of the valve reaches the upper limit is inferred as the maintenance judgment index of the flow control device.